Various bioactive glass compositions are known in the field. They are able to bond to bone and soft tissue, and they may be used for stimulating tissue or bone growth in a mammalian body. Bioactive glass also typically guides the formation of new tissue, which grows within said glass. When bioactive glasses come into contact with a physiological environment, a layer of silica gel is formed on the surface of the glass. Following this reaction, calcium phosphate is deposited to this layer and finally crystallized to a hydroxyl-carbonate apatite. Due to this hydroxyl-carbonate apatite layer the resorption of the bioactive glasses is slowed down when inserted into mammalian bodies.
Other types of resorbable glass compositions are also known in the field. Resorbable glasses are not necessarily bioactive, i.e. they do not form a hydroxyl-carbonate apatite layer on the glass surface. Resorbable glass compositions are used in the glass fibre industry to resolve the problem of glass fibres ending up e.g. in lungs during installation of glass fibre insulation. Disappearance of the fibres is preferably relatively fast, so that no detrimental effects are caused to the body. One resorbable glass composition is disclosed in EP 0 412 878. The fibres are degraded within 32 days. Such a degradation rate is, however, too fast for most medical applications, for example for screws or pins for fixing bone defects or fractures.
EP 0 915 812 B1 and EP 1 484 292 A1 disclose biosoluble glass composition to improve occupational health and safety. WO 03/018496 A1 discloses anti-inflammatory, wound-healing glass powder compositions. U.S. Pat. No. 6,482,444 B1 discloses silver-containing bioactive sol-gel derived glass compositions to be used in implanted materials, for preparation of devices used for in vitro and ex vivo cell culture.
EP0802890B1 discloses a bioactive glass composition with a large working range. Devitrification problems are circumvented by adding potassium and optionally magnesium to the glass.